ABSTRACT
PURPOSE: Conflicting results have been reported for western populations on associations of serum insulin-like growth factor I (IGF-I) and major IGF-binding protein-3 (IGFBP-3) with the risk of prostate cancer. However, few data have been available for oriental populations. We undertook a matched case-control study in a low-risk Korean population to extend our knowledge about potential associations. MATERIALS AND METHODS: Serum IGF-I and IGFBP-3 levels were determined for 330 men (165 cases and 165 healthy age-matched controls). Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for the association between plasma IGF levels and prostate cancer. We also investigated the potential influence of the associations according to clinical risk for advanced disease at diagnosis. RESULTS: We noted that the risks of prostate cancer were unrelated to the IGF-1 level and IGF-I/IGFBP-3 molar ratio. In contrast, a strong inverse association was observed between IGFBP-3 levels and the risk for prostate cancer. Men in the highest quartile of IGFBP-3 levels had a 71% reduced risk of prostate cancer compared with men in the lowest quartile (OR=0.29, 95% CI: 0.11-0.64, P(trend)<0.001). Subgroup analysis revealed a significant inverse association between plasma IGFBP-3 and the likelihood of a high risk prostate cancer. CONCLUSIONS: Plasma IGFBP-3 levels were inversely associated with the risk of prostate cancer and the likelihood for high-risk disease, suggesting that IGFBP-3 plays a protective role against prostate cancer in the Korean population.